Numerical modelling of multiphase flow in unsaturated deforming porous media

Ghorbani, Javad; Nazem, Majidreza; Carter, John

doi:10.1016/j.compgeo.2015.09.011

Cited by 57 publications

(22 citation statements)

References 66 publications

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“…The majority of the numerical models developed for simulation of flow and deformation in unsaturated porous media are in the framework of the finite element method (FEM) . Another class of numerical methods, referred to as meshfree methods (MMs), has gained popularity, particularly during the past two decades, since they overcome some intrinsic difficulties of the FEM .…”

Section: Introductionmentioning

confidence: 99%

“…The majority of the numerical models developed for simulation of flow and deformation in unsaturated porous media are in the framework of the finite element method (FEM). 11,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] Another class of numerical methods, referred to as meshfree methods (MMs), has gained popularity, particularly during the past two decades, since they overcome some intrinsic difficulties of the FEM. 43 In MMs, a series of nodes define the problem domain and a predefined connectivity of the nodes is avoided.…”

Section: Introductionmentioning

confidence: 99%

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Fully coupled elastoplastic hydro‐mechanical analysis of unsaturated porous media using a meshfree method

Ghaffaripour

Esgandani

Khoshghalb

et al. 2019

Num Anal Meth Geomechanics

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Summary This paper presents the first application of an advanced meshfree method, ie, the edge‐based smoothed point interpolation method (ESPIM), in simulation of the coupled hydro‐mechanical behaviour of unsaturated porous media. In the proposed technique, the problem domain is spatially discretised using a triangular background mesh, and the polynomial point interpolation method combined with a simple node selection scheme is adopted for creating nodal shape functions. Smoothing domains are formed on top of the background mesh, and a constant smoothed strain, created by applying the smoothing operation over the smoothing domains, is assigned to each smoothing domain. The deformation and flow models are developed based on the equilibrium equation of the mixture, and linear momentum and mass balance equations of the fluid phases, respectively. The effective stress approach is followed to account for the coupling between the flow and deformation models. Further coupling among the phases is captured through a hysteretic soil water retention model that evolves with changes in void ratio. An advanced elastoplastic constitutive model within the context of the bounding surface plasticity theory is employed for predicting the nonlinear behaviour of soil skeleton. Time discretisation is performed by adopting a three‐point discretisation method with growing time steps to avoid temporal instabilities. A modified Newton‐Raphson framework is designed for dealing with nonlinearities of the discretised system of equations. The performance of the numerical model is examined through a number of numerical examples. The state‐of‐the‐art computational scheme developed is useful for simulation of geotechnical engineering problems involving unsaturated soils.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fully coupled elastoplastic hydro‐mechanical analysis of unsaturated porous media using a meshfree method

Ghaffaripour

Esgandani

Khoshghalb

et al. 2019

Num Anal Meth Geomechanics

View full text Add to dashboard Cite

show abstract

“…For instance, Muraleetharan and Wei and Ravichandran and Muraleetharan developed the governing equations for the seismic behavior of unsaturated soils and used a two stress state approach [3,4]. Whereas, Uzuoka and Borja (2012), ShahbodaghKhan et al (2015), and Ghorbani et al (2016) have used the effective stress approach and single stress framework [5][6][7]. It has been stated that single stress approach can eliminate the need for multiple constitutive parameters for nonlinear response of unsaturated soils.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, in dynamic analysis of the response of unsaturated soils, various studies have employed different assumptions for the effective stress parameter. For instance, Uzuoka and Borja (2012), and Ghorbani et al (2016) have used degree of saturation as the effective stress parameter whereas Shahbodagh-Khan et al (2015) have considered it to be a function of matric suction which takes the hydraulic hysteresis into account.…”

Section: Introductionmentioning

confidence: 99%

“…Zienkiewicz et al (1990) were first to study the dynamic behavior of unsaturated soils [2]. Their pioneering work has been followed by a couple of other studies in which different aspects of the unsaturated soils' response to the seismic excitations have been investigated [3][4][5][6][7]. Different constitutive equations and assumptions in these studies have been considered.…”

Section: Introductionmentioning

confidence: 99%

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Seismic response of earth dams considering dynamic properties of unsaturated zone

2016

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Abstract. It is conventionally assumed in the analysis and design of earth dams that the soil located above the phreatic line, i.e. the uppermost seepage flow line, is completely dry. However, there is often an unsaturated flow of water through an unsaturated zone above this borderline and variation in moisture content in this zone results in variation of matric suction throughout this region. Variation of matric suction, in turn, results in variation of effective stresses in this zone. In this research, the seismic response of earth dams in terms of the displacement and acceleration at the crown of the dam as well as the stress distribution in the dam body is investigated. Taking into account the effect of unsaturated zone, a comparison is made to investigate the effect of conventional simplification in ignoring the dynamic characteristics of the unsaturated zone above the phreatic line and the more complicated analysis which includes the unsaturated zone. A function for the soil-water retention curve (SWRC) was assigned to the soil in the unsaturated zone to determine the variation of matric suction in this zone and analyses were made using finite difference software (FLAC). Results are then compared to the conventional method for homogeneous dams. In these analyzes the soil shear modulus was assumed to vary with the mean effective stress both for saturated and unsaturated zones. Among various results, it was notable that the history of crest x-displacement, and acceleration show higher values in models accounting for the unsaturated region. It was attributed to the considerably lower values of damping ratio in the crest region in the unsaturated models.

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Vertical dynamic impedance of end‐bearing pile groups embedded in homogeneous unsaturated soils

Shan

et al. 2022

Num Anal Meth Geomechanics

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Although soil is typically an unsaturated (three‐phase) medium, previous studies on the dynamic impedance of pile groups primarily considered the piles embedded in either the single‐phase or fully saturated (two‐phase) soils. In this work, the dynamic impedance of end‐bearing pile groups embedded in homogeneous unsaturated soil subject to a vertical time‐harmonic load is analytically obtained. The soil is modeled as a three‐dimensional axisymmetric continuum, and both the radial and vertical displacements as well as the influence of the saturation degree on the soil's dynamic shear modulus are considered. The governing equations of vibrating unsaturated soil are uncoupled by virtue of the potential function and operator decomposition methods. The attenuation function of soil displacement, surrounding soil resistance factor, and vertical dynamic impedance of a single pile are derived from the pile−soil compatibility conditions. Pile‐to‐pile dynamic interaction factors are then derived and used, along with the superposition principle, to find the vertical dynamic impedance of end‐bearing pile groups in the frequency domain. The proposed analytical solution is verified by comparison with two benchmark solutions. Finally, the influence of various parameters on the dynamic response of end‐bearing pile groups is determined.

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Numerical modelling of multiphase flow in unsaturated deforming porous media

Cited by 57 publications

References 66 publications

Fully coupled elastoplastic hydro‐mechanical analysis of unsaturated porous media using a meshfree method

Fully coupled elastoplastic hydro‐mechanical analysis of unsaturated porous media using a meshfree method

Seismic response of earth dams considering dynamic properties of unsaturated zone

Vertical dynamic impedance of end‐bearing pile groups embedded in homogeneous unsaturated soils

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